This invention relates to chemical compounds, such as epoxy resin adhesives, which include an epoxy resin and a curing agent, and more particularly, to a method and apparatus for preparing such chemical compounds to be mixed for reaction.
Epoxies are furnished in two parts, an uncured resin containing a chemical compound of the epoxide group and a catalyst consisting of an amine or other compound that acts as a curing agent. Curing is effected by mixing the curing agent with the epoxy resin just prior to use and hardening is rapid. The epoxy resin and the curing agent are packaged separately to prevent premature curing.
In the two-part mixing process, an exacting amount of the epoxy resin and the curing agent must be measured prior to mixing of the two parts together. Typically, the measured amounts of epoxy resin and curing agent are blended in a container for mixing and the ultimate reaction process necessary. The requirement for exact measured portions of the epoxy resin and the curing agent gives rise to potential inconsistencies and error. Also, the drying potential of each part of the two-part epoxy resin and curing agent product can render the ultimate mixing process inoperative because of the drying of one part causing poor results in mixing the two parts together. Moreover, improper mixing may bring about poor results and over-mixing one part over another can result in waste. Also, these mixing processes can be messy, particularly When the epoxy resin and curing agent are in liquid form.
In one known process for preparing an epoxy mixture, the epoxy resin and the curing agent are introduced into two different syringe-like containers and forced out of the containers by depressing a plunger causing both parts to be extruded in liquid form through a common outlet, thus mixing both elements of the epoxy. Although this arrangement provides controlled mixing of the two elements of the epoxy mixture, the epoxy is extruded in liquid form and as such is not end-user oriented. Also, the product may have limited shelf life.
Another process for preparing an epoxy mixture is disclosed in Re. U.S. Pat. No. 30,843. In this disclosed process, an epoxy resin and a curing agent are extruded in side-by-side relationship forming a tape. After extrusion, the tape which is formed is rolled into any convenient length and packaged. The epoxy tape is formulated so that the epoxy resin and the curing agent are contained in separate bands making up the tape in such a manner that the epoxy resin itself will not cure until substantially equal lengths of the respective bands are combined into a substantially uniform mixture.